One mutation in this structure causes hypophosphatemic vitamin D-resistant rickets, and abnormal numbers of CGG repeats in its FMR1 gene may cause mental retardation. This structure is coated with RNA by the Xist gene, and its monosomy causes Turner syndrome. Inactivated to form a Barr body, its recessive mutations are linked to hemophilia and red-green colorblindness. Reduced fertility resulting from Klinefelter syndrome affects males with two copies of this structure. 
One mutation in this structure causes hypophosphatemic vitamin D-resistant rickets, and abnormal numbers of CGG repeats in its FMR1 gene may cause mental retardation. This structure is coated with RNA by the Xist gene, and its monosomy causes Turner syndrome. Inactivated to form a Barr body, its recessive mutations are linked to hemophilia and red-green colorblindness. Reduced fertility resulting from Klinefelter syndrome affects males with two copies of this structure. For 10 points, name this chromosome possessed once by males and twice by females.
One mutation in this structure causes hypophosphatemic vitamin D-resistant rickets, and abnormal numbers of CGG repeats in its FMR1 gene may cause mental retardation.
{X} chromosome